1. Field of the Invention
The present invention relates generally to data transfer and, more particularly, to systems and methods for multicasting packets of information.
2. Description of Related Art
Routers receive data on physical media, such as optical fiber, analyze the data to determine its destination, and output the data on physical media in accordance with the destination. Routers were initially designed using a general purpose processor executing large software programs. As line rates and traffic volume increased, however, general purpose processors could not scale to meet these new demands. For example, as functionality was added to the software, such as accounting and policing functionality, these routers suffered performance degradation. In some instances, the routers failed to handle traffic at line rate when the new functionality was turned on.
To meet the new demands, purpose-built routers were designed. Purpose-built routers were planned and constructed with components optimized for routing. They not only handled higher line rates and higher network traffic volume, but also added functionality without compromising line rate performance.
A purpose-built router may include a number of input and output ports from which it transmits and receives information packets. A switching fabric or other transmission medium may be implemented in the router to carry the packets between the ports. In a high-performance purpose-built router, the switching fabric may transmit a large amount of information between a number of internal components.
Typically, purpose-built routers may be required to “multicast” information (i.e., send the same data from one source to multiple receivers). One type of multicast is a “single stream multicast,” in which a copy of the same packet is sent to different logical interfaces (e.g., different frame relay or virtual LAN) that are all part of the same physical interface. However, the nature of multicasting may place uneven demands on certain resources within the router. Also, multicasting may adversely impact the quality of service (i.e., the performance, such as transmission rates and error rates, of a communications channel) of the router.
Thus, there is a need in the art to more efficiently implement multicasting within routers.